Heat treatment of steel.



UNITED STATES PATENT OFFICE.

SAMUEL WALES, F MUNHALL, lPENNSYLVANIA, ASSIGNOR T0 CARNEGIE STEELCOMPANY, OF PITTSBUBG, PENNSYLVANIA, A; CORPORATION QFJNEW JEBSEY.,

HEAT Tnnermnnr or STEEL.

1210 Drawing.

To all whom it may concern:

7 scription.

Be it known that I, SAMUEL S. WALES, of Munhall, Allegheny county,Pennsylvania, have invente a new and useful Improvement in HeatTreatment of Steel, of which the following is a full, clear, and exactde My invention .is designed to provide an improved method of heattreatment of steel, whereby a ,more uniform strength is obtainedthroughout the piece, and is particularly designed for armor or vaultplates or-deck plates, though it may be applled to plate, the ingot iscast in the usual way, forged, annealed, then carburized on its face,then usually 'reforged, and then fibered by the usual process. The lateis then' sometimes toughened by furt or treatment, and is thenin acondition for final water-hardening. The heat treatments for such platesand other heat-treated steels are uniform over the, extent of the plateand take no hecount of the variationsin chemical composition of thevarious parts of the plate,-

caused by segregation of-its contained metallo'ids during cooling'andsolidifying of the ingot.- The carbon is most liable to segreation, andother elements may be calculated in carbon equivalents. This segregationtakes place to a greater extent in the top portion of the ingot than inthe lower portion, and where the bottom end or top end of the plate ishereinafter mentioned I refer to that portion of the plate which comeserably roughly in proportion tothe segre.

from the bottom portion or from the top gar-Hon, of the ingot as thecase may be. 7 y subjecting the whole plate or portion to be treatedto'a uniform heating, great difierences in tensile strength between thetop and bottom of the'ingot may be developed;

and I have discovered that such differences may be largely reducedand-possibly eliminated by raising the plate to a temperature whichvaries between the two ends and prefgation.

In practice a "great improvement is made in the plate by modifying thelast annealing process and varying the heat of difi'erent parts of theplate. *ThusI first preferably raise the plate to a'temperature between800 and 900 degrees C and quench with water or other cooling liquid to atemperature below 300 degrees; The

laced in the furnace, and the eat so reguated therein that the end ofthe plate which is subject to the greater segregation, will be raised toa temperature higher than the other end of the plate. The variation intemperature of one end of the plate'from the other may be accom lished1n any desired manner, for examp e, the temperature of one end of thefurnace-in which the plates are heated, may be raised or lowered abovevorbelow that of the. opposite end to a degree necessary to give thedesired difference in temperature in the opposite ends of the plate,bya-proper manipulation of the air and gas valves used on such furnaces.This tem erature may be calculated by many wel -known methodsto attain acertain desired tensile strength. The average ofthese temperatures ispreferablycbetween 500 and 700 degrees (3., and the dilf er'ence intemperature between the twoends may be as high as 150 degrees. The plateis then cooled as desired; In a test on a plate,

twenty feet in lengthshOWing such a segre'gation in carbon that -thecontent was .37 at the top end and .27 at the bottom end,- was subjectedto the varying heat treatment just described with an annealingtemperature of about 620 degrees at the top end and about 520 degrees atthe bottom end; and

v Specification of Letters Patent. Patented Dec, 20, 1910, I Appficationfiled April 21, 1908. Serial No. 428,307.

late is then the tensile strength of test pieces taken from these endsdid not differ over one per cent.

Theadvantages of my invention will be ap reciated by those skilled inthe art. The di erent strength'in different parts of the plate orportion to be treated resulting from the uniform heat treatmentheretofore given is overcome, and the platemade substantially uniform orthe variation in strength greatly reduced b the variation in thetemperature imparte to the various parts. My

invention does not add to the cost of production, but does addmaterially to thevalue of the plate making its strength more uniform inthe different parts.

Many variations ma 'be made in the above described treatment 0 the steelwithout'de parting from my invention, since What I claim 'is: .1. Themethod of metalloids in different proportion different parts thereof,consisting in h ating the treating steel contalning' lateand raising onepart of the portion to iie-treated to a different temperature from thatof another portion at the same. depth. Y 2. The method of heattreatingsteel, consisting in'heating the plateor portion'to be treated andvarylng the heat of-the different parts accordin 'to the proportion ofmetal loids containe therein.

e3. The'method of heat-treating steel havin different proportions ofmetalloids in di er'ent parts thereof, consisting in heatn'g the plat'eand raising those portions contamin .a greater proportion of metalloidsto a higher heat than-those portions containmg alower proportion ofmetalloids.

4. The method of treatingsteel, consisting I in heating a plate to ahardening temperaformly heatin ture, then ture, then quenching it,- and,then tin-unithe length. of the plate to temperatures etween 500 and 700degrees cent1grade, and then cooling the same.

5. The method of treating steel, consisting. in heating a plate to ahardening temperaquenching' it, then heating it to diflierenttemperatures at different portions of the plates with relation to thedifference in composition caused by segregation.

6. The method of treating steel, consisting in heating a plate to ahardening temp'eratu're, then quenching it, then heating the differentportions of the plate to temperatures varymgdirectly to the proportionsof carbon contained 1n the said dliferent portions of said plate.

7. The method of treating steel, consisting in annealing a plate, in

hyheating the different portions of the plate to temperatures betweenoOOdegrees and 700 said different portionsheat at temperatures varyingdirectly to the proportion of 'car-.

degrees centigrade, being subjected t0 bon'contained therein, and thencooling the same. a I v 8. The method .of treating steel plate, in whichthe component elements are more highly segregated at one end than at thewhich the various component elements have become segregated,

other, which consists in heatingthe plate to tion of its face.

In testimony whereof, I have hereunto set my hand. I

' SAMUEL s. WALEsL Witnessesi D. T, Jon'ns, C.-v L. WILsoN,

portion of its face 7

